The TrayCell is a fibre-optic ultra-micro cell designed for the UV/Vis micro volume analysis of DNA/RNA and proteins.
The TrayCell is designed for measurements e.g. of DNA/RNA or protein samples and enables highly accurate analysis of extremely small samples with remarkable reproducibility. The dimensions of the TrayCell are equivalent to a standard cuvette in order to work in most spectrophotometers.
TrayCell - Photometric Micro Volume Analysis in the nanolitre range
DNA/RNA - simply analysed.
Typical applications of the TrayCell
- nucleic acid analysis
- determination of the incorporation frequency of fluorescent dye labels (FOI)
- protein analysis (A280, BCA, Lowry etc.)
- all UV/Vis analysis utilizing the wavelength range of 190 to 1100 nm
Functional principle
Due to the integrated beam deflection and the use of fibre-optic cables it is possible to measure the sample directly on the surface of the optical window. The cap with mirror provides a well-defined optical light path and prevents the sample from drying up. The measurement remains reproducible because the sample will not be enriched by evaporation of the solvent.
During filling and cleaning stages, the cell remains in the photometer. This guarantees a continuously identical position of the aperture in the light beam and no variation in comparison to the reference measurement.
Light paths and sample volumes
Using the 1 mm or 0.2 mm cap creates a de- fined optical light path of 1 mm and 0.2 mm respectively. This generates virtual dilution factors of 1:10 or 1:50 in comparison to a measurement with a standard 10 mm cuvette. This feature saves time and avoids dilution errors. If desired, samples can be retrieved after the measurement for further processing. The required sample volume for the 1 mm cap is 3 μl to 5 μl and for the 0.2 mm cap 0.7 μl to 4 μl.
With the Hellma TrayCell the average dynamic range for dsDNA is between 2 ng/μl and 5000 ng/μl. The average dynamic range depends strongly on the type of photometer used.
Quantification of Nucleic Acids
To determine the nucleic acid concentration in solutions, the solutions’ absorption value is used at a wavelength of 260 nm (A260). The following function, derived from Lambert-Beer‘s Law, is applied:
Concentration [ng/μl] = Absorbance (260 nm) x Factor
(with Factor = Sample Specific Factor x Virtual Dilution Factor)
The Sample Specific Factor represents the specific absorbance for example of a sample of 50 ng/μl dsDNA that gives a reading of 1 Abs (A260), measured with an optical light path of 10 mm inside a standard cell. Due to the optical light paths of the TrayCell of 0.2 mm or 1 mm, a Virtual Dilution Factor of 50 or 10 must be taken into account additionally.
For the different types of nucleic acid solutions the average dynamic range of the absorbance relating to the concentration (ng/μl) results as follows (depending on the lightpath):
| 1 mm lid, (Virtual Dilution Factor of 10) [ng/µl] * |
0,2 mm lid (Virtual Dilution Factor 50)[ng/µl] * |
Measurement range [ng/µl] * |
|
| dsDNA | 13 – 850 | 63 – 4250 | 6 – 8500 |
| ssDNA | 9 – 629 | 46 – 3145 | 5 – 6290 |
| ssRNA | 10 – 680 | 50 – 3400 | 5 – 6800 |
| Oligo | 8 – 561 | 41 – 2805 | 4 – 5610 |
| * typical absorbance, measured with an ordinary spectrophotometer | |||
